Glue spreader

ABSTRACT

A roll glue spreader for applying an adhesive coating to one side of veneer strip or sheets wherein a set of transverselyspaced endless chain conveyors, extending fore and aft of a pair of spreader rolls and fitting inside mating grooves formed on the circumference of the bottom spreader roll, carry the veneer through the spreader while maintaining a positive drive on the veneer at all times and preventing any tendency of the veneer to wrap-up on the bottom spreader roll.

United States Patent Pape et al.

[ 51 Oct. 3, 1972 GLUE SPREADER [72] Inventors: Wayne Pape, Gold Beach; Doyle J.

4/1950 Gustin ..118/239 X 1,912,553 6/1933 Wagner ..118/239 X 2,372,894 4/ 1945 Gustin ..1 18/239 X 2,094,349 9/1937 Carlson ..118/239 X 765,507 7/1904 Noyes ..118/239 X 1,202,337 10/1916 Whitney et a1. ..118/227 Primary Examiner.lames Kee Chi Attorney-Daniel P. Chernoff ABSTRACT A roll glue spreader for applying an adhesive coating to one side of veneer strip or sheets wherein a set of transversely-spaced endless chain conveyors, extending fore and aft of a pair of spreader rolls and fitting inside mating grooves formed on the circumference of the bottom spreader roll, carry the veneer through the spreader while maintaining a positive drive on the veneer at all times and preventing any tendency of the veneer to wrap-up on the bottom spreader roll.

2 Claims, 5 Drawing figures GLUE SPREADER BACKGROUND OF THE INVENTION This invention relates to a roll glue spreader for applying adhesive to veneer strip or sheets preparatory to the lay-up of the veneer into a plywood panel and in particular relates to a modified roll spreader especially adapted for applying an adhesive coating to one side of core material formed from a plurality of relatively narrow strips of veneer, held together either by edge-gluing or by adhesively-secured tape or string and fed through the spreader along its weak dimension, i.e., with its grain orientation aligned transversely to the direction of travel of the veneer.

In the manufacture of plywood the various layers of veneer, comprising face, center, back and core material, are laid-up in proper sequence by a crew or by automatic machinery with a coating of urea, resin or other suitable adhesive applied between the layers preparatory to the insertion of the panel into the glue press. In a lay-up of a typical five-ply panel consisting in sequence of a back layer, a core layer, a center layer, another core layer and a face layer, glue is applied between the layers immediately prior to their lay-up into the panel.

While curtain coaters and glue sprayers are to some extent used in the industry, the most common means of applying the adhesive coating is through the use of a glue spreader comprising a pair of spreader rolls, either biased together by spring action or having resilient backing so as to create a pressure contact of the spreader rolls on the respective surfaces of the veneer material as it is fed through the nip of the spreader. A trough containing a liquefied adhesive, typically a water-soluble thermosetting adhesive mixture, is positioned above or laterally of the top roll of the spreader in communication therewith so that the glue coating on the circumferential face of the roll is constantly replenished. One or more helical grooves or other configured surface indentations are formed on the surface of the upper roll so as to retain the glue as the surface of the roller receives it from the trough. The roller then applies it in the manner of a squeegee onto the upper surface of the veneer strip or sheet as the roll surface comes in contact therewith.

In prior art roll glue Spreaders of the type described, it is known for the veneer strips or sheet to be delivered to the infeed side of the spreader by a first endless conveyor belt, with the veneer being carried through the spreader machine itself by the rolling pressure exerted at the nip of the rollers, and thereafter a second endless conveyor is provided at the outfeed to off-bear the veneer with its freshly-applied coating of adhesive. Typically, and especially in a case of core material formed of a plurality of relatively narrow strips of veneer held together either by edge-gluing or with adhesively-secured tape or string in the manner disclosed for example in Jacobson US. Pat. No. 3,490,974, the veneer material is fed into the spreader along its socalled weak direction, that is, with its grain orientation aligned transverse of the direction of travel of the material. As the veneer strip or sheet has relatively little rigidity when fed in this direction, it is necessary to provide expedients, in the form of guard plates, fingers, shoes or similar guiding means, to insure that the veneer maintains a planar configuration and passes directly through the nip of the spreader rolls and then onto the second conveyor without curling and wrapping-up either on the infeed side or on the bottom or upper spreader rolls.

In prior art roll glue Spreaders, any tendency of the veneer strip or sheet to wrap around the upper spreader roll is effectively prevented typically by the provision of a piano wire guide, comprising a plurality of thin wires spaced transversely across the length of the roll and secured fore and aft of the roll so as to impose a barrier preventing the veneer from curling onto the upper roll. In the case of the bottom roll tendency of the veneer to curl and wrap around is more likely, because of the influence of gravity, and is more difficult to remedy. Conventionally, a guard plate or shoe arranged on the infeed end of the spreader, and a corresponding finger arrangement similarly positioned at the outfeed side, are provided to minimize any tendency of the veneer material to deviate from the intended plane of travel and wrap around the infeed conveyor of the bottom roll. However, the provision of the aforedescribed guiding means is not altogether satisfactory because, in order to prevent wrapping up of the veneer on the bottom spreader roll, it is desirable that the input conveyor extend closely adjacent to the spreader rolls so as to virtually tuck the veneer into the nip of the rolls. Such an arrangement, with the guide means extending closely adjacent to the spreader rolls, increases the likelihood of the guide means picking up an appreciable amount of glue slop from the spreader rolls where it can then transfer to the bottom surfaces of oncoming plies of veneer.

Accordingly, the need exists for more satisfactory means for guiding the travel of veneer material through the spreader rolls and maintaining it in the intended plane of travel so as to overcome the problems and disadvantages associated with the conventional guiding means heretofore employed in the art.

SUMMARY OF THE INVENTION The present invention relates to a roll glue spreader of the type described wherein, in lieu of conventional guiding means in the form of plates, shoes, fingers, etc. provided on the infeed and outfeed sides of the spreader rolls, the infeed conveyor, consisting of a set of transversely-spaced endless chains, is extended so as to pass through the nip of the rolls and then beyond, so that the veneer strip or sheets are carried by the infeed conveyor chains (which is driven at the peripheral speed of the rolls) directly into the spreader and then away therefrom. The conveyor chains rest in mating circumferential grooves formed on the bottom spreader roll so that as the chains pass through the nip of the spreader a uniform pressure contact, extending across the width of the rolls, is maintained on the surface of the veneer passing therebetween. As the bottom spreader roll and the conveyor chains are of metal construction, they are impervious and accordingly have but minimal tendency to pick up any glue from the upper spreader roll. Any appreciable accumulation of adhesive which does build up can be readily moved from the metal roll and chains by scrapers acting alone or in conjunction with washing apparatus. A

It is therefore a principal objective of the present invention to provide a new and improved roll glue spreader for applying an adhesive coating to one side of veneer strip or sheet material in a manner maintaining a positive drive on the veneer at all times and preventing any tendency of the veneer to wrap-up on the infeed conveyor or bottom spreader roll.

It is an additional objective of the present invention to provide a'roll glue spreader of the type described in which there is a minimal tendency for adhesive buildup in undesired areas of the spreader apparatus and where any adhesive accumulation in such areas can be readily removed.

It is a principal advantage of the present invention to providea modified roll glue spreader especially adapted for applying an adhesive coating to one side of plywood core material formed from a plurality of relatively narrow strips of veneer held together by tape or string and fed through the spreader rolls along its weak dimension.

It is a principal feature of the present invention to provide a roll glue spreader for applying an adhesive coating to one side of veneer strip or sheet material wherein a single set of transversely-spaced endless chain conveyors, extending fore and aft of a pair of spreader rolls and fitting inside mating grooves formed on the circumference of the bottom spreader roll, carry the veneer into, through and beyond the spreader.

The foregoing and other objectives, features and advantages of the present invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front sectional view of a prior artform of roll glue spreader provided with guiding means on the upper and lower spreader rolls for maintaining the veneer string along the desired plane of travel.

FIG. 2 is a front sectional view of a roll glue spreader modified in accordance with the teachings of the present invention.

FIG. 3 is a top plan view of the spreader apparatus depicted in FIG. 2.

FIG. 4 is an enlarged sectional view showing a detail of the construction of the bottom spreader roll.

FIG. 5 is a sectional view taken along the line 5-5 in FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, FIG. 1 shows a typical prior art form of roll glue spreader apparatus, designated generally as 10, for applying an adhesive coating to the upper surface of a veneer strip 12. This device conventionally comprises a pair of top and bottom spreader rolls 13, 14, either biased together by spring action or having resilient backing so as to create a pressure contact of the rolls on the respective surfaces of the veneer strip 12 as it is fed through the nip of the spreader. A bottom-opening trough 15 containing a liquefied adhesive 16 is positioned above the top roll 13 of the spreader in contact therewith so that the glue coating on the circumferential face of the roll is constantly replenished. Alternatively, the trough 15 may be positioned laterally of the spreader and a doctor roll provided in the reservoir to meter out the amount of adhesive supplied onto the spreader roll l3.

An infeed endless conveyor belt 18 delivers the veneer strip or sheets to the nip of the spreader where the rolling pressure of the spreader rolls takes over to carry the material through the spreader and deliver it onto an outfeed conveyor belt 19. In order to prevent any tendency of the veneer strip 12 to wrap-up on the upper roll 13, either at the infeed or outfeed ends, a piano wire guide 20 is typically provided, the details of which are best shown in FIG. 3. The guide, which is conventional, comprises a plurality of thin wires spaced transversely across the length of the upper spreader roll 13 and secured fore and aft of the roll so as to impose a barrier preventing the strip from curling onto the upper roll.

In order to minimize any tendency of the veneer material to similarly curl and wrap around either the end of the infeed conveyor belt 18 or the lower spreader roll 14 it is conventional 'in prior art devices to provide guiding means located at both the infeed and outfeed sides of the bottom spreader roll to maintain the strip in the desired plane of travel. In the exemplary prior art apparatus shown in FIG. 1, the guiding means on the infeed side takes the form of a flat plate or shoe 22 situated between and in the plane of the conveyor 18 and the nip of the spreader so as to virtually completely fill in the space between these two elements and in this manner block off any entry opening which the veneer strip 12 might have to curl downward beneath the plane of travel prior to being delivered into the nip of the spreader rolls.

On the outfeed side of the spreader it is also conventional to provide a spaced plurality of receiving or offbearing fingers 24 situated between and in the plane of the nip of the spreader and the outfeed conveyor 19. The receiving fingers 24 function in a manner similar to the input guide 22 to guide the veneer material in its transition from the spreader to the off-bearing conveyor and minimize any tendency of the material to curl downward and wrap around the bottom spreader roll 14. The above-described forms of guiding means as used in prior art spreader apparatus for preventing curling and wrapping of the veneer strip or sheet material onto the trailing end of the infeed conveyor or onto the bottom spreader roll are not altogether satisfactory for the reasons previously mentioned.

In FIGS. 2-5 there is illustrated a modified form of roll glue spreader according to the present invention in which improved means are employed to guide and convey the veneer material into and out from the spreader apparatus. In these figures, in which like reference characters refer to corresponding elements similar or equivalent to those of the prior art spreader device depicted in FIG. 1, the modified spreader 10 comprises a pair of respective top and bottom spreader rolls, 13, 14 through the nip of which veneer material is fed for depositing a coating of adhesive on the upper surface thereof.

As before a piano wire guide 20 is provided to prevent the veneer material from curling up and wrapping around the upper spreader roll 13. A horizontal endless conveyor formed of a plurality of transversely-spaced chains 32 carries the veneer strip or sheet material 12 into the nip of the spreader and then exiting therefrom. As depicted in the detail views of FIGS. 4 and 5, the individual chains 32 ride inside mating keyway grooves 34 formed in the circumference of the bottom spreader roll 14' as the chains pass through the nip of the spreader rolls and then on the return pass of the endless conveyor loop. The depth of the grooves 34 is preferably such that the chains ride substantially flush with the cylindrical surface of the roll.

Since the chain conveyor 32 provides a positive drive carrying the veneer material 12 through the nip of the spreader rolls, it is no longer necessary for a pressure bias to be present urging the top and bottom spreader rolls together so as to provide sufficient rolling friction to convey the veneer material through the apparatus. Also, the capacity of the motor drive rotating the respective top and bottom spreader rolls l3, 14 can be substantially reduced since the veneer transport function can be taken over entirely by the drive for the endless chain conveyor 32.

In order to minimize the buildup of adhesive on the lower portion of the spreader and prevent its transfer to the bottom side of the veneer material passing through the spreader apparatus, it is preferable that the surface of the bottom spreader roll 14 be made of metal or other hard, impervious material from which any glue deposit can be readily removed by scraping or washing. Such roll construction is to be contrasted with conventional spreader configurations in which the peripheral surface of the bottom as well as the top spreader roll is typically made of soft rubber or similar material so as to provide resiliency for a pressure bias exerted at the nip of the spreader but which undesirably traps and builds up hard-to-remove glue deposits because of the spongy character of the spreader roll material. While a spongy characteristic is very desirable for the top spreader roll which absorbs and transfers the liquefied adhesive 16 from the bottom of the trough 15 to the surface of the veneer, it is far from ideal for the peripheral surface of the bottom spreader roll in a single-surface glue spreader of the type referred to herein.

In lieu of a conveyor formed of a plurality of spaced metal chains, the transport of the veneer through the spreader apparatus can alternatively be provided by a horizontal endless conveyor formed of one or a plurality of corrogated metal belts of preferably open-weave mesh construction so as to minimize the pick-up and retention thereon of adhesive as the veneer is carried through the nip of the spreader.

As indicated previously, the modified roll glue spreader of the present invention is particularly suitable for use in applying adhesive to veneer core material 12 formed of a plurality of narrow strips of veneer held together by adhesively-secured string or tape 12a (see FIGS. 4 and 5) and fed through the spreader along its weak direction with the grain of the veneer perpendicular to the direction of travel.

it will be readily appreciated that with the modified spreader apparatus of the present invention where there is no break in the horizontal conveyor on which the veneer is supported, there is no possibility of the veneer curling up and becoming wrapped around the bottom spreader roll as was oftentimes the case, with prior art Spreaders of the type described.

The terms and expressions which have been employed in the foregoing abstract and specification are used therein as terms of description and not of limitation, and there is no intention, in the use of such terms and expression, of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.

What is claimed is:

1. A roll glue spreader for applying an adhesive coating to one side of planar material comprising:

a. A pair of top and bottom spreader rolls having a nip region therebetween through which said material passes,

. means for supplying a liquefied coating of adhesive onto the surface of said top spreader roll for transfer to the upper surface of said material as it passes through the nip of said spreader, and,

c. conveyor means for transferring said material through said nip region, said conveyor being comprised of a plurality of traversely-spaced endless chains and arranged in the form of a driven endless loop having an upper course and a lower course, the upper course serving to support and transport said material throughsaid spreader and the lower course returning underneath said bottom spreader roll, said endless chains of said conveyor being fitted within mating grooves formed on the circumference of said lower spreader roll.

2. The spreader apparatus of claim 1 wherein said planar material is veneer core formed of a plurality of relatively narrow strips of veneer secured together to form a unitary sheet which is fed into the nip of said spreader with its grain orientation aligned transversely to the direction of travel of said sheet into said spreader.

Patent No. 3,695,225 Dated October 3 l972 Inventor(s) Wayne Pape and Doyle J, Hall It is. certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 3 Line 37 Change "string" to strip-.

Signed and sealed this 13th day of February 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM PO-IOSO (10-69) USCOMM-DC 60376-P69 fir us, GOVERNMENT PRINTING OFFICE: 1969 o-aes-ssa 

1. A roll glue spreader for applying an adhesive coating to one side of planar material comprising: a. A pair of top and bottom spreader rolls having a nip region therebetween through which said material passes, b. means for supplying a liquefied coating of adhesive onto the surface of said top spreader roll for transfer to the upper surface of said material as it passes through the nip of said spreader, and, c. conveyor means for transferring said material through said nip region, said conveyor being comprised of a plurality of traversely-spaced endless chains and arranged in the form of a driven endless loop having an upper course and a lower course, the upper course serving to support and transport said material through said spreader and the lower course returning underneath said bottom spreader roll, said endless chains of said conveyor being fitted within mating grooves formed on the circumference of said lower spreader roll.
 2. The spreader apparatus of claim 1 wherein said planar material is veneer core formed of a plurality of relatively narrow strips of veneer secured together to form a unitary sheet which is fed into the nip of said spreader with its grain orientation aligned transversely to the direction of travel of said sheet into said spreader. 